Grinding wheels



R. E. DowNlNG T AL 2,803,098

GRINDING WHEELS Filed June 14, 1955 2 Sheets-Sheet 1 I\\ l!!! d NV ENTORS R0352!- E. DOWNING Emc B. James 'Aug 1957 R. E. DOWNING AL GRINDING WHEELS 2 Sheets-Sheet 2 I Filed June 14, .1955

INVENTORS RoBeRT' E. DOWNING time B. James 1 WM/ya ATTQRNEYS United States Patent GRINDING WHEELS Robert Ernest Downing, Redruth, Cornwall, and Eric Basil James, Camborne, Cornwall, England, assignors to Holman Brothers Limited, Cornwall, England, a company of Great Britain Application June 14, 1955, Serial No. 515,448

. Claims priority, application Great Britain June 15, 1954 8 Claims. (Cl. 51-273) This invention relates to means for preventing dust produced during grinding operations from spreading into the atmosphere of the working place and is applicable to both grinding discs which use one of the side faces of a grinding wheel and to grinding wheels which use the peripheral edge.

' Much of the dust generated during grinding operations and in particular the respirable small particles can be very dangerous to persons in the vicinity. While dust extraction systems are available which withdraw air and with it dust from a large area in the region of the machine, these systems are not satisfactory in that they are not always very efficient in removing the dangerous dust and in that they withdraw warm air from the working place, rendering air-heating apparatus inefiicient.

According to the present invention a dust extractor for a grinding wheel includes a vane so positioned and so shaped as to direct dust carried around with the wheel as it rotates into a duct for the removal of the dust.

By these means the high velocity air'streams set up by rotation of the grinding wheel are used in removing the dust and the dust, is removed from the immediate vicinity of the wheel as it is generated, that is to say at its source, so that it is unnecessary to remove from the working place large quantities of air surrounding the grinding wheel.

I The duct can be coupled to means for applying suction to withdraw the dust from it, for example a standard form of exhauster, but the use of the air streams generated by rotation of-the wheel enables a lower external suction to-beused than would otherwise be the case.

Preferably the leading edge of the vane is generally tangential to the periphery of the wheel and preferably it is radially adjustable so that it can be positioned as close as possible to the wheel without actually touching it.

There may be one or more vanes and if there are more than one each may be associated with a separate duct or they may be associated with a common duct. In one arrangement, only the last vane is radially adjustable.

However, according to a further form of the invention a dust extractor for a grinding wheel includes a duct adapted to be mounted to extend around a part of the circumference of the wheel and having one or more holes directed towards the edge surface of the wheel and a vane so positioned adjacent each hole and so shaped as to direct dust carried around with the wheel as it rotates into the duct.

The suction means can then be applied at a convenient place in the circumferential duct.

The invention may be carried into practice in different ways but two embodiments will be described by way of example with reference to the accompanying drawings in which:

Figure 1 is an end view of a cowl for a stationary grinding wheel embodying the present invention,

Figure 2 is a side view of. the cowl shown in Figure 1, and

Figure 3 is a side view of a cowl embodying the invention for a swing frame grinder in which it is necessary to 8 3 8 Patented Aug. 20, 1957 have a relatively large part of the circumference of the wheel uncovered.

The cowl shown in Figures 1 and 2 has two sides 1 and 2 separated by a circumferential shell 3 having in it an opening of perhaps to expose the portion of the grinding wheel 4 which is to be used. Plates 5 extend radially inwards from the sides 1 and 2 around the opening so as just to clear the sides of the grinding wheel. A clamp 6 is secured to the side 1 so that the cowl can be attached to the body of the grinding machine and a pipe 7 provides a connection to a source of suction in the form of a conventional exhauster (not shown).

At the end of the opening where the rotating wheel enters the cowl the circumferential shell is spaced some distance from the periphery of the wheel as is shown in Figure 2, while from a position about diametrically opposite the centre of the opening the circumferential shell 3 is comparatively close to the periphery of the wheel.

Near the end of the cowl at which the grinding wheel 4 enters it is positioned a curved vane 8 which extends throughout the width of the grinding wheel and which in section (as is shown in Figure 2) has its leading edge, that is to say the edge which is first encountered by the rotating wheel, approximately tangential to the periphery of the wheel and closely radially spaced from it. The other end of the vane lies in a hole 9 in the circumferential shell so that the trailing edge of the vane which is approximately radial lies on the outside of the shell. A duct communicating with the-hole is formed on the outside of the shell by means of a semi-cylindrical shell 11 welded to the main body of the cowl.

This duct communicates with the pipe 7. As the wheel rotates, dust generated during grinding is carried with the air stream generated by the rotating wheel into the cowl where it is stripped from the wheel by the vane 8 and drawn bythe source of suction through the hole 9 and into the pipe 7, whence it can be led to a filter or other dust disposal apparatus. I

A second similar vane 13 is positioned in the cowl almost opposite the opening and just before the circumferential shell becomes closely spaced from the periphery of the grinding wheel. 7 The second vane 13 is positioned in a similarhole 14 in the shell which communicates with the same pipe 7 so that dust not stripped from the wheel by the vane 8 may be stripped bythe vane 13.

In certain applications a vacuum of four feet of water in conjunction with the air streams set up by the rotating wheel will be sufiicientto remove at least the better part of the dangerous dust generated in the grinding operation.

The cowl shown in Figure 3 for use with a swing frame grinder is quite similar to the cowl shown in Figures 1 and 2. However, it extends only about two-thirds of the periphery of the grinding wheel since in using a swing frame grinder it is necessary to have a larger portion of the circumference of the wheel unenclosed.

The circumferential shell is double walled, one wall 15 being spaced radially inwards from the outer wall 16 to form a duct which lies circumferentially around a portion of the periphery of the grinding wheel. This duct communicates at one end with a pipe 17 for connection with a source of suction. The inner wall 15 of the circumferential duct has four inwardly-directed holes approximately equally angularly spaced, there being one at each end of the duct. Vanes 18 are positioned in three of the holes and these are similar to the vanes 8 and 13' shown in Figure 2. The vane at the trailing end of the duct is radially adjustable so that it can be positioned close to the periphery of the grinding wheel even though the grinding wheel becomes worn. At the end of the duct connected to the pipe 17 the equivalent of a vane is provided by a flange 20 on the inner wall 15 which is bent towards the grinding wheel, and a corresponding flange 21 on the lower end of thepipe 17. Between them these flanges 20 and 21 provide a short air passage leading into the circumferential duct.

The holes in the inner wall of the duct are graded in size to equalise the suction, holes further from the pipe 17 being of larger area. The outer wall 16 is stepped inwards at 23 just past the second .vane 'to make the circumferential duct smaller in cross-sectional area for the last part vof its length.

In operation dust generated during grinding is collected in the duct in a similar manner to that described with reference to the embodiment shown in Figures 1 and 2 and thereafter is withdrawn through the pipe 17. Some dust which is not carried into the cowl due to the opening into the cowl being some distance from the working part of the grinding wheelperiphery is collected in slots 24 formed in the lower face of the pipe 17 asis described more fully inBritish patent'specifica tion N 0. 9,755 55 A vacuum pressure of about two feet six inches to three feet six inches of water is suitable for extracting dust with this apparatus.

A cowl somewhat similar to the cowl shown in Figure 3 but without one of the side faces may be used for collecting dust generated by a grinding wheel using one of the side faces. i

What we claim and ,desire to secure by Letters Patent 1. A dust extractor for a grinding wheel which includes a cowl and means for mounting said cowl adjacent and surrounding part of the circumference of the Wheel, a suction duct incorporated in the cowl, said duct having a wall adjacent to the curved edge of the wheel, said wall being formed with a hole facing the curved edge of the wheel, an aerofoil stripper vane positioned in the hole and projecting inwardly from the said wall towards the wheel, the stripper vane being curved between its outer end and its inner end, the said outer .end extending generally radially to the wheel with its edge extending across the hole in the direction transverse to the wheel so that the hole affords ports on both sides of the vane for the passage of suction-induced airstreams through the wall into the duct past both faces of the stripper vane, and the said inner end of the vane extending approximately tangentially to the wheel circumference in the direction opposite to the direction of peripheral movement of the wheel edge.

2. A dust extractor as claimed in claim '1 in which the duct extends parallel with the axis of the wheel.

3. A dust extractor as claimed in claim 1 in whieh the vane is adjustable .relativelyto the duct wall in the dir s wa nd y fr m he cur d edge of h wheel.

4. A dust extractor as claimed in claim 1 in which the duct is coupled to a source of vacuum which applies to the duct a pressure less than that of the ambient-air by an amount in excess of the pressure head of one foot of water.

5. A dust extractor as claimed in claim 4 including a second similar duct provided with a similar vane and also coupled to a source of vacuum which applies to the duct a pressure less than that of the ambient air by an amount in excess of the pressure head of one foot of water.

6. A dust extractor for a grinding wheel including a cowl and means for mounting said cowl adjacent and surrounding part of the circumference of the wheel, a suction duct incorporated in the cowl, said duct extending circumferentially around a part of the curved edge .of the wheel. said duct having a curved inner wall adjacent to and circumferentially surrounding a part of the curved edge of the wheel, said inner wall being formed with holes angularly spaced apart around the curved edge of the wheel and facing the said curved edge, aerofoil stripper vanes positioned one in each hole, each stripper vane being curved between its outer end and its inner .end, the said outer end extending generally radially :to the Wheel with its edge extending across the hole in the direction transverse to the wheel edge so that the holeafl fords ports on both sides of the vane for the passage of suction-induced.airstreams through .the wall into the duct past both faces of the stripper vane, and the said inner end of the vane extending approximately tangentially to the wheel circumference in the direction opposite to the direction of peripheral movement of the wheel edge.

7. A dust extractor as claimed in claim 6 in which the vane is adjustable relatively to the duct wall in the directions towards and away from the curved edge of the wheel.

8. A dust extractor as claimed in claim .6 in which the duct is coupled to a source of vacuum which applies to the duct a pressure less than that of the ambient air by an amount in excess of the pressure head of one foot of water.

References Cited in the file of this patent UNITED STATES PATENTS 760,834 Yarnell May '24, '1904 790,943 Weber May 30, 1905 956,762 Furrow May 3, 1910 1,174,659 Bilicki May 7, 1916 1,406,914 Virgilio 'Feb. 14, 1922 1,891,696 Trimble Dec. 30, 1932 2,499,582 Harrison Mar. 7, 1950 FOREIGN PATENTS Sweden -.-.--.-..-.--r:r:e.--.r--.- 

